Fuel system



Aug. 24, 1943. D. SAMIRAN 2,327,373

FUEL SYSTEM Filed MarchlS, 1959 6 Sheets-Sheet 1 D. SAMIRAN Aug. 24, 1943.

FUEL SYSTEM Filecl March 13, 1939 S SheetS-Sheet 2 TroR/vg 1/5 Aug. 24, 1943.

D. SAMIRAN 2,327,373

FUEL SYSTEM Filed March 13, 1939 6 Sheets-Sheet 3 a 12:? i lr WVE/VTOR QZDaV/Dv SAM/RAN ArraR/Vsfs Aug. 24, 1943. D, SAMIRAN 2,327,373

FUEL SYSTEM Filed March 13, 1939 6 Sheets-Sheet 5 6 is- (93 (90/88 rm a0 ez 77 f/TTGRNEY'S Patented Aug. 24, 1943 UNITED STATES PATENT OFFICE;

FUEL SYSTEM David Samiran, Fail-field, Ohio Application March 13, 1939, Serial No. 261,542

21 Claims. (C1. l58-36) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

The present invention relates in general to fuel systems provided with a plurality of separate fuel sourcw and more particularly to a fuel system in which the contents of fuel containers representative of such fuel sources are automatically connected in predetermined order to a source of fuel consumption.

it is an object of my invention to make use of fuel pressure drop in either the source selector portion or the fuel delivery portion of my fuel system, induced by' successive fuel container exhaustions, to effect automatic connection of said source of fuel consumption with a succeeding full fuel container.

A further object of my invention is to disclose,

individually, certain new and novel fuel systemstion taken in connection with the accompanying drawings, it being clearly understood that the same are by way of illustration'and example only and are not to be taken as in any way limiting the spirit or scope of my invention. The spirit and scope of my invention is to be limited only by the prior art and by the terms of the appended claims.

Referring to the drawings, in which numeral of like character designate similar parts throughout the several views:

Fig. l is a diagrammatic representation of a first embodiment of my invention;

Fig. 2 is a similar representation of a second embodiment of my invention;

Fig. 3 shows in schematic form a third embodiment of my invention;

Fig. 4 is a mechanical representation of the central portion of Fig. 3;

Fig. 5 shows a modification in the fuel delivery portion of Fig. 2;

Fig. 6 is a cross-sectional view of one embodiment of my air-vapor eliminator and pressure responsive switch;

Fig. 7 is a cross-sectional view of a detached form of my pressure responsive switch;

Fig. 8 is a cross-sectional view of my switch pressure regulator;

Fig. 9 is a cross-sectional view of one embodiment of my fuel pressure regulator;

Fig. 10 is a cross-sectional viewof a further embodiment of my fuel pressure regulator;

Fig. 11 is a cross-sectional view'of a further embodiment of my air-vapor eliminator and pressure responsive switch;-

Fig. 12 is a cross-sectional view of a modified form of pressure responsive switch cooperating with a venturi;

Fig. 13 is a diagrammatic plan view of a modified threecircuit interrupter; and

Fig. 14 is a sectional view taken on the line i4|4 of Fig. 13.

In the first embodiment of my invention, I seek to accomplish two objectives. Firstly, I am concerned with providing means whereby a source of fuel consumption, such as an internal combustion engine fuel injector or carburetor, may be readily interconnected with any one of a plurality of fuel containers through simple manual turning of the control handle of a conventional type of selector valve. Since each of the fuel containers of Fig. l is provided with a remotely reading fuel gauge, and due to the further fact that the reading elements of these gauges bear a special relationship to the aforesaid control handie, it becomes but a simple matter to register a pointer provided upon the said control handle with any desired reading element, thereby assuring that a desired fuel container is operably connected with the source of fuel consumption. Secondly, I seek to provide means for automatically turning the aforesaid selector valve from a container in which all fuel has just been exhausted to the next fuel container in selector valve order from which fuel has not yet been exhausted.

The following parts are common to all three embodiments of my invention: For mere purposes of illustration, I provide three fuel containers I, 2, and 3, respectively. Obviously, a greater or less number of containers may be provided without in any way departing from the spirit of my invention. Empty fuel container I, as well as full fuel containers 2 and 3, are separately connected to a like number of inlets provided in a selector valve 4. A single outlet in the selector valve 4 is appropriately connected to a fuel strainer 5. An outlet in the fuel strainer 5 is commonly connected to an engine driven fuel pump 6, a manually operated wobble pump 1, and a pressure relief valve outlet in an engine carburetor noted below. Outlets in the fuel pump top of the air-vapor eliminator 8a. In Figs. 2 and 3. the pressure responsive switches 3b are separated from the air-vapor eliminator 8b in a manner more fully described in connection with the latter two figures. Subject to certain limitations, the pressure responsive switch 911 may also be separated from the air-vapor eliminator 3a in a manner and for a purpose more fully described in connection with the description of the second embodiment of my invention. A fuel outlet of the air-vapor eliminator 8a is connected to the inlet of an engine fuel injector l0, while an air-vapor outlet of the eliminator 8a is connected with the fuel container 3. An engine carburetor may equally well be substituted, in Fig. 1, for the fuel injector ID. A pressure regulator outlet of the injector I is connected to the inlet side of the fuel pump 6.

I desire to especially note, at this point, that while the fuel containers I, 2 and 3 of Fig. 1 are illustrated as elevated with respect to the fuel pump 6, the aforesaid interpositioning may be reversed. If the fuel pump 6 is positioned above the aforesaid containers, there are height limits between pump and containers and between aircraft and ground beyond which the vacuum type pumps generally employed in aircraft will not function. Later reference is made to a further limitation existing in present fuel delivery systems requiring pressure control at source of consumption and how I propose to completely overcome such limitation.

In the embodiment of my invention shown in Fig. 1, the fuel containers I through 3 are shown to comprises a casing H provided with a vented filler i2 and a tank element l3 of a remotely reading fuel level gauge noted below. The tank element 13 is composed of a lever mechanism l4 supported by the body IS, a bellows l6 and a float II. The bellows I3 is fluid filled and in the showing of Fig. 1 is at maximum expansion, due to tank empty condition of the fuel container I. An outlet of each bellows I6 is operably connected with a pre-selected dial actuating element [8a, lb, or 180, of the above-mentioned remotely reading fuel level gauge by means of pipes l9a, I91), and I90. Each of the actuating elements I80, 18b, and l8c is composed of a housing 20, a bellows 2| and a bellows rod 22 provided at its outer extremity with a gear rack 23. For the mere purpose of schematic representation, the elements 18a, I81), and i8c, are illustrated as lying in a common plane normal to a later referred to shaft utilized to turn the selector valve 4. Like positioning of remotely reading fuel gauges 24a, 24b, and 24c, is also provided for upon a control panel 25. A shaft 26, projecting from the bottom of each of the aforesaid gauges, is operably connected with an associated gear rack 23 by means of'a pinion gear 21. From the cross-sectional showing of Fig. 1, it is readily apparent that extension of the liquid filled bellows l6 causes like and simultaneous extension of the at mosphere filled bellows 2!, as the whole obviously forms a liquid sealed system. Thus the pointer of the indicator dial 240. is seen to register a tank empty condition, while like pointers on the indicator gauges 24b and 24c show a tank full condition,

The selector valve 4 (as shown in Figs. 1 and 2) is composed of a housing 28 provided with three (90 degree spaced) inlets 29a, 29b, and 290, which are separately connected with the fuel containers 1, 2, and 3 by means of pipes 30a, 30b, and 300, respectively, and with a central outlet 36. Its central portion is provided with a truncated conical cavity 3| adapted to receive a cork lined taper valve 32. The valve 32 is provided with a short driving shaft 33, protruding from its face of greater diameter and with an L-shaped passageway 34 having its shortest end projecting through the valve face of lesser diameter such that it is coaxially located with respect to theshaft 33 and having its long end disposed normal to the axis of the shaft 33 such that it may be successively registered with the longitudinal axes of the housing inlets 29a, 23b, and 290. Installation of a cover plate 35 completes assembly of the selector valve 4. In order that the selector valve 4 may be remotely controlled from the panel 25, I have provided an extension shaft 31. The shaft 31 passes through the mid portion of the panel 25 and is fixedly coupled to the short driving shaft 33 by means of a sleeve 38 and driving pins 38. A control handle 40 is fixed to the opposite end of shaft 31 by means of a driving pin II. The significance of a ratchet wheel 42a, fixed to the mid portion of the shaft 31, will be dealt with during discussion of the automatic control of the selector valve 4.

It is important that an operator of the fuel system disclosed in Fig. 1 can at all times manually adjust the selector valve 4 to any desired tank.- I make this possible by positioning the three inlet ports 29a, 23b, and 290, of the selector valve 4 and the remotely reading gauges 2|a, 24b, and 240 mounted upon the panel 25 in plan coincidence, in combination with like positioning of an arrow or pointer 43 provided upon the'control handle 40 and the long end'of the L-shaped passageway 34 provided in the selector valve 4 in like plan coincidence. The operator need only refer to the pointer positions of his gauges 23a, 24b and 24c,'in order to exactly ascertain fuel content in the fuel containers I, 2, and 3, respectively. Observing that the container I is in tank empty condition, he thereafter has the choice of registering the arrow 43, with either the gauge 24b associated with the fuel container 2 or the' gauge 24c associated with the fuel container 3, both of which indicate their respective containers as being in a tank full condition.

In order that automatic operation of the selector valve 4 may be more readily understood, it is essential that Fig. 6 be briefly described. It hasalready been stated that this figure is composed of an air-vapor eliminator 8a and a pressure responsive switch 90. mounted directly to the top thereof.

The air-vapor eliminator 3a is composed of a cup shaped housing 44 surmounted at its open end by a cover plate 45. The cover plate 45 is also adapted for separate attachment to the pressure responsive switch 30 and includes provision for pipe fitting attachment. The cup shaped housing 44 is provided at its lowermost extremity with a horizontal inlet 48, a vertical outlet 41, a drain boss l8 and a drain plug 49. The upper end of the outlet 41 is recessed to receive and fixedly hold the tube like bottom extremity of a cup shaped deflector 50. A cylindrical sieve 3|, sealedto the open end of the housing H by means of a gasket 52 and the cover plate 45, has its lower tube like extremity adapted to be piloted into that portion of the deflector 53 which projects downwardly into the upper end of the outlet The cover plate 35 is provided with an angular flange 53 adapted to receive the open end of a cup-shaped float guide 54. The bottom of the float guide 54 is provided with a further cup-shaped guide 55 adapted to receive the low- .er extremity of a valve mechanism 58. The latter mechanism is composed of a tube 51 flxed to casing halves 58a and 58b of a float 58 (which may be internally reinforced, as shown, if desired), said tube having an outer collar 88 and inner collar 8| fixed to its lower extremity by means of a pin 82 and an inner collar 88 soldered or otherwise fixed to its uppermost extremity of a needle valve 84; of a valve stem 85; and of a valve spring 88. The base of the ieedle valve 84 rior of the housing 44 is in direct communication with a vent line 18 through passageways 'I I, 12, i3 and 14. The vent line 18 is in turn in communication with the atmosphere through the containers 3 and vented filler I2 shown in Fig. 1.

In the pressure responsive switch 8a, a cylindrical housing is separated into an upper and a lower cavity 18 and 11, by means of a common wall 18. A bearing boss 18 depends from the central portion of the wall 18. A bellows 88 is designed to seal the lower cavity 11 from fluid intercommunication with a tapped hole 8| leading directly into the interior or the housing 44 of the air-vapor eliminator 8a (1. e., when the outermost tainer 8, and the vented filler I 2, as may be readily seen by joint reference to Figs. 1 and 6. with introduction of fuel through the inlet 48 provided in the base of the air-vapor eliminator 8a, raising of the fuel level within the housing 44 brings about ultimate full up positioning of the valve mechanism, whereupon the needle valve 84 seals the central aperture provided in the valve seat 88 (as shown in Fig. 6). Thereafter, additional rising of the fuel level within the housing 44 causes air trapped in the upper portion thereof, in the tapped hole 8|, and in that portion of the pressure responsive switch 8a which lies intermediate of the under surface of the bellows 88 andthe uppermost surface of the cover plate 45, to be ultimately expelled as noted below. Upon predetermined increase in the aforesaid pressure, repositioning of parts causes the conedges of the bellows are firmly clamped between I a flange 82 provided upon the bottom of the housing H, a gasket 88, and the upper outermost surface of the cover plate 45). The space between the top surface of the bellows 88 and the inner surface of the lower cavity 11 is directly vented to the atmosphere by means of a passageway 84. Two electrical binding posts 85 and 88 are fixed to the top of a dome 81 of insulating material (having a number of lightening holes drilled therethrough) Cut-outs 88' are provided in the uppermost dome surface for installation of a fixed contact 88, short coupled to the binding post 88', and a movable contact 88, long coupled to the binding post 85 by means of spring leaves 8i. The mid portion of the leaves 9| is raised or lowered with reference to the base of a bellows stem 82 by vertical adjustment of a nut 83 provided upon the upper threaded end of the bellows stem 82. By means of this adjustment, spacing of the contacts 89 and 88 may be varied to any desired gap. Prior to assembly of the above electrical parts, a washer 84 is slipped over the necked down upper portion of the bellows stem 82, a gasket 85 is placed in the bottom of the upper cavity 18, and a thin flexible diaphragm 88 is placed over the aforesaid two parts. A spring 81 and spring retaining washers 88 and 88 are next added, after which the dome assembly described above is positioned as shown in Fig. 6, and the nut 83 is screwed down to the desired adjustment. The assembly is completed tacts 88 and 88 to be separated in the manner shown in Fig. 6. Actual operation of my fuel system in aircraft indicates that the trapped air referred to hereinabove is gradually driven out through the vent line 18 until the combined interiors of the housing 44 and the lower cavity 11 in the housing I5 are completely liquid filled. So long as the aforesaid predetermined fuel pressure is maintained or exceeded, the contacts 88 and 88 will remain in the open position of Fig. 6. However, in the event of continued operation of the fuel system of Fig. 1 with the container I in the "empty condition shown, the fuel pump 8 will no longer be able to deliver fuel to the inlet 48 and the housing 44 of the air-vapor eliminator will merely act as a reserve reservoir for limited auxiliary fuel delivery to the fuel iniector I8. After predetermined depletion of this auxiliary supply, the valve mechanism 56 will assume the down position previously referred to above. The foregoing will be simultaneously followed by downposition of the bellows 88, resulting in closing of the contacts 88 and 98. The significance of alternate opening and closing of the aforesaid contacts is dealt with immediately below.

Having fully described the construction and operation .of the air-vapor eliminator 8a and pressure responsive switch 9a, I now propose to disclose how these parts, as a unitary assembly, cooperate with a signal lamp IN, a solenoid motor I82, an impulse timer or motor control I83, a relay I84, a battery I85, an internal combustion engine ignition switch I88, an electric circuit I81 and a circuit cut-out switch I88, to eifect automatic turning of the selector valve 4 from any :itank empty condition to a tank full condi- The solenoid motor I82 (shown in Fig. 1) is composed of a solenoid I88 disposed normal to the auxiliary shaft 31 and lying in common plane with the ratchet wheel 42a, a mountin panel II8 provided with a positive terminal I II and a hinged dog H2 consisting of connecting links H3 and driving pins II4. Due to hinged attachment of the rear end of the dog II2 to the solenoid I89, the ratchet wheel 42a may be freely manually adjusted by the control handle 48 in a clockwise direction. Following each outward stroke or impulse of the solenoid I88, the forward end of the dog H2 is drawn upwardly and backwardly to a point where it automatically falls down" into engagement with the next-tobe-engaged toot of the ratchet wheel 42a. While Fig. 1 shows provision for clockwise manual adjustment of the selector valve 4 only, it is to be understood that the ratchet wheel 42a may be provided with an appropriate mechanism permitting manual adjustment of the selector valve 4 in a counter-clockwise direction as well as the present clockwise direction.

The motor control I08 is composed of a motor element H5 and a make-and-break element III. For simplicitys sake, the motor element H5 is diagrammatically represented by conventional commutator, brushes, coil and ground, with positive lead" connected to a terminal I". The motor element H5 is geared to a ratchet wheel II8 (of the make-and-break element II8) such ass-nave resulting in an electric current being delivered to terminals I23 (panel), I24 (lamp), I2I (relay), and to the binding post 88 (pressure responsive switch). Thereafter, the operator presses down upon a push button I2I of the signal lamp III to make certain that the light portion thereof is properly functioning. If the. latter be true, he then closes the cut-out switch I08 of the electrical circuit I01, which is the last manual operation necessary to assure automatic adjustment of the selector valve 4.

pump to thereafter build up suiflcient pressure to eifect opening of the pressure responsive switch 9a. In the second embodiment of my invention, I propose alternative utilization of the motor control I03 (in lieu of a later referred to circuit cut-out switch). The latter usage should be accompanied by an increase in the number of teeth provided upon the ratchet wheel I I8 or the turning rate of the wheel II8 should be increased for reasons fully discussed herein below. One lead" of the make-and-break element I I8 is commonly connected to the positive lead of the motor elementv H5 and the terminal II'I (of the motor control I03), while the other lead" thereof is connected to the remaining terminal I I 9 of the motor control I 03.

The relay I04 is provided with make-andbreak terminals I20 and I2I, and with a positive coil terminal I22. Terminal, I20 is connected to the terminal III of the solenoid motor I02. Opposite terminal I2I is commonly connected to the binding post 88 of the pressure responsive switch 9a (see Fig. 6), to a positive terminal I23 provided upon a small control panel I33a, to the positive pole of the battery I05 and to the positive testing terminal I24 of the signal lamp IIlI. Positive (relay) terminal I22'is connected to the terminal IIS of the motor control I03. The other terminal 1, of the motor control I 03, is commonly connected to a second terminal I25 provided upon the control panel I33a (through the circuit cut-out switch I08), to a positive operating terminal I28 of the signal lamp IOI, and to the binding post 85 of the pressure responsive switch 8a (see Fig. 6). The aggregate of the above described connections may be' taken as constituting the electric circuit I01 referred to at the commencement of the second preceding paragraph above.

Functioning of the electrical circuit .I0'I can be most readily understood when described in correlation with the following operating steps observed in connection with the fuel system shown in Fig. 1. For off-engine condition, no fuel is flowing, the ignition switch I08 is off, and the electrical circuit I01 is inoperative. On the other hand, for on-engine condition, it must be assumed that fuel is flowing', that pressure incident thereto maintains contacts 89 and 90 in the open condition of Fig. 6, and that the ignition switch I08 is on;

On-engine" functioning of the electrical circuit I01 is divided into the sub-operating steps of "closed contact" condition of the pressure responsive switch 8a, in effect so long as the fuel pump remains continuously connected with an empty fuel container (as would be the case in Fig. 1), and open contact condition of the pressure responsive switch 8a shown in Fig. 8, which latter condition is in effect so long as an uninterrupted supply of fuel is delivered to the fuel pump 8 by the selector valve 4.

Let us first trace sub-circuit operation under closed contact condition. Obviously, thereunder, the selector valve 4 must be turned to a tank full condition (either by means of the control handle or the solenoid motor I02) if the engine connected with the carburetor I0 is to continue to function. Regardless of which of the aforesaid means is employed, it is further important that an operator of the fuel system of Fig. 1 receive immediate visual warning of the above condition. The latter is simply and automatically accomplished. With closing of the contacts 88 and 80 of the pressure responsive switch 8a, electric current from the battery Ill passes directly throughvthe light portion of the signal lamp IM to the ground, via the binding posts 85 and." and the terminals I25, I20 and I28. I wish to call attention, at this point, to the fact that in so far as the control panel I884: is concerned, closing oi. the above contacts 00 and immediately effects direct connection of panel terminal I 25 with the positive pole of the battery I05.

The second sub-circuit, under the above closed contac condition, concerns primarily the motor control I08 and secondarily the solenoid motor I02 which it controls. So long as the pressure responsive switch 8a remains closed, electric current will continue to 'pass from the terminal I25 of the control panel I380 to the ground of the control motor I02 (through the cut-out switch I08, the terminal II! and the motor element II5) resulting in continuous slow counter-clockwise turning of the ratchet wheel II8. Since the single tooth of the latter wheel initially starts from a position closely approximating the showing of Fig. 1, a relatively short period only is required to effect closing of the make-and-breal: element II8. Thereafter two things occur, one very brief in its duration and the other much longer in duration.

Firstly, closing of the make-and-break element II 8 produces an immediate closed circuit across terminals I I1 and H0 of the motor control I03. Current from the terminal I25 of the panel I83a thereafter passes directly to the ground of the relay I04 (through the cut-out switch I08 and the terminals H1, H8 and I22), closing the breaker portion I80 of the relay I04. Closing of the relay I04 effects secondary current flow from terminal I25 of the panel Ifla to the ground of the solenoid I08 (through binding posts 05 and 88 of the pressure responsive make-and-break element IIO.

assure theratchet wheel 42a. Thedog III remains in extended position imtil the tooth of the ratchet wheel II3 has turned sufficiently to'open the Thereafter, the forward end of the dog III is drawn upwardly i 5 to the outlet ofthe fuel pump t through suitable pipe connection with the tappedhole 3| provided in the cover plate 4!. The above limitations'are two-fold. Firstly, the fuel system must incorpoii rate an engine carburetor or an engine fuel in jector (if the. latter its own air-vapor eliminator) that is directly connected to the outlet of its fuel pump; it e., there is no air-vapor eliminator present. Secondly,'the outlets of the fuel containers of the system must be provided andbaekwardlyintoapositionfromwhichitfalls downwardly into operable engagement with the next oncoming tooth of the ratchet wheel 42o. secondly, the motor element II! continues to turn until the fuel pump 3 builds up'sum cient pressure to effect openingof the pressure responsive switch 86. at which time the tooth of the ratchet wheel III has rotated-into a position closely approximating the showing of Fig. 1. Should, for any reason whatsoever, the automatic adjustment hereinabove described fail to function; the operator of the fuel system of Fig.1 has but to open the circuit cut-out switch I33 to be thereafter completely free to accomplish any manual adjustment of the selector valve 4 he may desire under guidance of the pointer readings of gauges 24a, 24b and 24c.

In the second embodiment of my invention, (shown in Fig. 2) I continue to seek accomplishment of the two objects enumerated in connection with the first embodiment thereof, Throug slight modification of the "ratchet scheme" of Fig. l, I am able to accomplish manual adjustment of the selector valve 4 in both clockwise and counter-clockwise directions. In the means for accomplishing automatic turning of the aforesaid selector valve, I provide a mechanism which assures more exact registration of the selector valve 4 upon connection with any container in which fuel still remains, unexhausted.

Fig, 2 has been materially simplified by omission therefrom of the triple showings of fuel containers (I through 3), tank elements (I3), dial actuating elements (I8) and remotely reading fuel gauges (24) formerly incorporated in Fig. 1. To further clarify wiring details, only a limited central portion of the control panel 25 is shown in full outline, the outer edges thereof being shown in phantom. It should be clearly understood that theaforesaid omission of fuel gauge parts is not intended to convey the impression that these parts should necessarily be omitted.

from an actual aircraft installation representative of Fig. 2.

I now refer to certain new part substitutions accomplished in Fig. 2. It should be noted that in the place of the impulse timer or motor control I03 of Fig. 1 I substitute a circuit cutout switch I3I, that in lieu of the single wire" electric circuit III'I of the same figure I substitute a double wire" electric circuit I32, that in lieu of the "two terminal" control panel I33a I substitute a three terminal control panel I33b (having a new terminal I34 replacing the four ground showings of Fig. 1) and that in lieu of the "combined air-vapor eliminator 8a and pressure responsive switch 90. I substitute separated" air-vapor eliminator 8b (i. e., the eliminator 8m with a plug I35 inserted in the tapped hole Si in the cover plate 45) and pressure responsive switch so.

I have previously stated in connection with the first embodiment of my invention, that, subject to certain limitations, the pressure responsive 1 sure responsive switch (as in Fig. 1) and at the with short stand pipe extensions having a pre-. determined opening 'at the base of each. The latter provides a suificient partial pressure drop to effect "closed circuiting of the system's pressame time assures a predetermined reserve fuel supply during the period in which the system's selector valve is moving. from tank empty" to A,

tank full" condition. I

Returning to the part showings of Fig. 2, since the pressure responsive switch so is no longer directly pressure connected to the air-vapor eliminator, I provideindependent pipe connection between one bellows element of the pressure responsive switch 8b and the outlet of the fuel pump 8, the said connection forming part of a switch pressure regulator I36, the construction details of which are fully disclosed in Fig. 8. I

also provide pipe connection between a second bellows element of the pressure'responslve switch 3b and the induction system of an aircraft super charged engine. Fig. 7 discloses theconstruction details of the new pressure responsive switch 9!). The latter is brought into operable connection with the extension, shaft 31 of the selector valve 4 by means of a control disk I31 (fixed to shaft 31) provided with tripping cams I380, I38b, a v

and I380.

sible desirability of substituting the motor control I03 (of Fig. 1) in lieu of the circuit cut-out switch l3I shown in the second embodiment of my invention. In such an event, the rate of turning of the ratchet wheel II8 should be markedly in creased (over that suitable for the first embodiment of my invention) or the single tooth shown in Fig. 1 should be supplemented by a plurality of such teeth. The necessity for incorporating one or the other of these two changes will become more apparent as the description of Fig. 2 progresses. It is sufficient to note, at this point, that in the second embodiment of my invention inter-action of the control disk I31 with the pressure responsive switch 9b effects proper stoppage of the selector valve 4 upon registry with the next fuel container in tank full" condition. In Fig. 1, each recurring impulse of the solenoid I02 registers the selector valve 4 with a new fuel container, regardless of whether the latter be in tank full" or tank empty condition.

In order that the second embodiment of my automatic operation of the selector valve 4 may be more readily understood, it is essential that Figs. '1 and 8 be briefly described. The pressure responsive switch 9b (shown in Fig. 'l) is composed bellows element I46 is fixed in continuation of the lower cavity MI by means of a'gasket I41 and switch 9a (of Fig. 1) can be directly connected a holddown ring I48 provided with a dust cover I have previously called attention to the pos I49. The free ends of bellows elements I43 and I46 are utilized to effect longitudinal displacement of a switch carriage I50, composed of an upper carriage element II, a lower carriage el ment I52, two spacer rods I53, nuts I54 and lock washers I55. The spacer rods I53 are guided in their longitudinal movement by two associated and coaxially disposed holes provided in parts I43 through I48, respectively.

The upper bellows element I43 is composed of an annular top plate I56, a bellows I51 soldered to the inner edge thereto, a cup-shaped bottom plate I 58 with outer edge soldered to the bellows I51 and an upstanding shaft I59 fixed to the central portion of the bottom plate I56. The shaft I59 is guided in the holddown plate I 45 by means of a. bushing I66. The holddown plate I45 is further suitably tapped for introduction of an upwardly projecting stud IBI, provided with an adjusting hole I62 and a check nut I63. Prior installation of the latter part. a circular sheet I64 of insulating material is placed upon the top of the holddown plate I65 and a vertical vent hole I65 is drilled through both parts.

The lower bellows element I46 is composed of an annular top plate I66, a'bellows I61 soldered thereto, and a bottom plate I68 likewise soldered to the bellows 61. The bottom plate I68 is provided with a central opening I69 surrounded by an upstanding cylindrical portion I10 having oppositely disposed slots I1I closed at their open ends by a snap ring I12.

The lower carriage element I52 is composed of a cross-bar I13 having a central opening I14, a holddown spring I15, and a spring loading or compression adjuster I16. The adjustor I16 I comprises a centrally flanged stud I11 with both ends threaded, a spring seat I18 with lateral projections I19 adapted to sl de longitudinally in the slots "I (of bottom plate I66), a gasket I80, 8. lockwasher FBI and a check nut I82. Upon appropriate loosening of the check nut I82, adjustment is readily accomplished by means of a screw driver slot I83 placed in the bottom of the flanged stud I11. Turn ng of the aforesaid stud causes the spring seat I18 to be raised from the "bottom position" showing of Fig, 7 to a to p9- sition in which further upward movement is prevented through contact of the projections I19 against the snap ring I12. This adjustment assures a wide range of varying spring compressions tending to maintain the switch carriage I 56 in the down or what is later herein referred to V insulation blocks I89 and ISO, the whole being fixed to the top surface of the cross-bar I63 by means of screws HI, 8. plain washer I92 and a lock washer I93.. The contactor arm element I66 consists of a hollow bar I64 journalled to the bosses I85 by means of a pin I95 and having a pin I35 about which the contactor arm element I86 pivots.

Before proceeding with a description of Fig. 8. I desire to note that that portion of the upper cavity I40 (01 the pressure responsive switch to) lying immediately exterior of the outside surface of the upper belloi 3 element I43 is adapted to be directly fluid connected with the switch pressure regulator I36 (as shown in Fig. 2), the interior of the upper bellows element I43 being atmosphere vented through the vertical vent hole I66 drilled in the holddown plate I45 and the circular sheet I64 of insulating material. I further desire to note that that portion of the lower cavity I4l lying exterior of the inside surface of the lower bellows element I46 is adapted to be directly fluid connected with the induction system of a supercharged aircraft engine in a manner and for a purpose later referred-to herein, the exterior of the lower bellows element I46 being atmosphere vented through a horizontal vent hole 20I provided in the dust cover I49, In the event that the second embodiment of my invention Is employed in conjunction with an aircrsit equipped with an unsupercharged engine, or an engine in which the supercharger does not effect the fuel injector or carburetor, the interior of the lower bellows element I46 is directly vented to the atmosphere.

The switch pressure regulator I36 (shown In Figs. 2, 5 and 8) is composed of a housing 232,

with an inlet 203, an outlet 204 leading into and out of a pressure regulator element cavity 245 and a by-pass 286 leading directly out of the inlet 203, and of a pressure regulator element 203 disposed within and sealing the aforesaid cavity 205. A bailie element 201 is operably connected to the by-pass 206. It consists of a housing 263, a gasket 2I0, five staggered baiile plates 2 and attaching screws 2I2. The element 201 prevents undesired fluid escapage from the pressure responsive switch 9b. It should be noted (by crossreference to Fig. 2) that the inlet 203 is operably connected to the outlet of the fuel pump 6, that the outlet 204 is operably connected to the inlet 46 of the air-vapor eliminator 6b, and that the baflie element 201 (forming a continuation of the by-pass 206) is operably connected to the upper cavity I40 of the pressure responsive switch 3b. Conventional means is provided for eliminating initial air trapped within the upper cavity m,

upon initial flow of fluid from the pressure regulator I36 to the upper cavity I40 of the pressure responsive switch 9b.

Prior to entry into a description oi the pressure regulator element 208, I desire to note that the design of its spring loading or compression adjustment is identical to that of the compression adjustor I16 of the pressure responsive switch lb (shown in Fig. 7). The element 206 (consisting cam I96 upon the upper outer surface thereof, a I

compression spring I91, a. support I 98 (composed of insulation material), a metallic roller I99 and a pin 200 for securing the roller I69 to its support I66. It should be noted that the apex of the V- shaped portion of the contact plate I86 is slightly more remotely located from the top surface of the cross-bar I83 than is the longitudinal aids of the of an entirely sell contained and therefore readily removable sub-assembly is composed of a. body portion 2| 3 provided with a top plate 2 having a. central opening 2| 5 surrounded by a depending cylindrical portion 2I6 with o positely disposed slots 2" closed at their open ends by a snap ring 2I8, a conical valve US with a "bypass" passageway 220 through the seat portion thereof, a holddown spring 22I, and a compression adjustor 222. The adjustor 222 comprises a centrally flanged stud 223 with both ends threaded (one of which has a vented cavity for guidance of the stem portion of the conical valve 2I9), the spring seat I16, the gasket I66, a new gasket 224, lockwire 225 and 226, and a check nut 221. The screw driver slot I 83 placed in the top or the flanged stud permits adjustment'the of in a manner identical to adjustment of the adiustor I16. of the pressure responsive switch 61) (shown inFlgJl).

The switch pressure regulator I30 operates as follows: During active operation (1. e., duringhllturnings) of the fuel pump 6; fuel .entering the I inlet 202 is accomplishing 'tworesults. Firstly, it

is inducing one or the other of two rangea'of pressure upon the upper cavity I40 of the pressure responsive switch 91). If the rate of discharge .through the by-passes 220 provided in the conical valve 2I9 is low, a "low pressure" reaction insuffi- -'side surfaceof the lower bellows element I46 cient to materially compress the-holddown spring- W I (of-switch 017) results. On-the other hand.

if the rate of discharge through the aforesaid by-passes 220 is high, a high pressure" reaction sufllcient to fully compress the holddown spring I15 (of switch 9b) results. Under full engine revolution, approximately one second only is required to effect the last named result upon fuel entry in the rotor portion of the pump 6. Secondly, fuel entering the inlet 202 is inducing continuous secondary flow of fuel from the outlet 204 to the air-vapor eliminator 6b and from thence to the engine carburetor I0 operably connected therewith. The pressure magnitude of this secondary flow of fuel (in so far as the switch pressure regulator I36 is concerned) is controlled by means of the regulator element 206. Should momentary fuel pressure in the inlet 203 "build up in excess of desired pressure, the head portion of the conical valve 2I9 moves off its associated seat. thus increasing flow of fuel through the outlet 204 of, the switch pressure regulator I36. The fuel injector I0 includes (as an integral part of its own structure) a pressure relief valve 226 whereby fuel pressure in excess of a predetermined value; occurring exteriorly of the outlet 204 of the switch pressure regulator I36, is automatically by-passed to the pu p The two phased operation of the pressure re sponsi've switch 9b (shown in Figs. 2 and '7) is as follows: By way of illustration. only, let it be assumed that the compression adjustor 222 is first adjusted such that a steady flow of fuel under five pound pressure is delivered by the by-pass 200 of inlet side of the fuel the switch pressure regulator I36. Under such ent in the upper cavity I40, of the pressure responsive switch 9b. Therefore, a second ad-.

justment of the'compression adjustor I16 of the latter switch must be made such that the spring I15 thereof will be sufficiently compressed to permit upward movement of the switch carriage I into a position disposing the contactor arm cam I96 coincident with the dotted +P" outline shown at the to of Fig. '7. The significance of the latter +P cam positioning is later discussed below.

The second phase of operation ofthe pressure regulator switch 9b (shown in Figs. 2 and '7) is concerned with application of the second embodiment of my invention (shown in Fig. 2) to an aircraft equipped with an engine in which the super- I,

is directly fluid oonne cted with the induction system of the aforesaid supercharged engine. This effects complete compensation for the above fuel pressure increase, the detailed character of connecwhich is fully explained hereinbelow (in 'tion with the description of Fig. 5). Having fully described the construction and operation 'of the pressure responsive switch 9!: l

and the switch pressure regulator I36, I now propose to disclose howthese parts cooperate with the control disk I21, circuit cut-out switches I06 and I3I and electric circuit'l32 (of Fig. 2) and with the signal lamp, IOI, solenoid motor I02,

relay I04, battery I05 and ignition switch I06 (of- Figs. 1 and 2), to effect automatic turning of the selector valve 4 from any tankempty condition to a tank full condition. In lieu of the motor a control I03 employedin the first embodiment of my invention, I substitute the circuit cut-out switch I3I, the operating arm of which is operably connected to a hinged dog 229. The engaging tip of the dog 229 is held in initial horizontal attitude bymeans of a spring 220. Upon energization of the solenoid motor I02, the forwardend of the dog 229 moves outwardly and slightly upwardly, which movement simultaneously carries the operating arm of the switch I3I into an "off 'position. The circumstances under which the solenoid motor I02 is so energized are dealt withbelow.

In the double wire" electric circuit I32, interconnection of the battery I05 .with the signal lamp IOI, the relay I04 and the ignition switch I06.is fundamentally the same as interconnection of like parts in the single wire" electric circuit I01 of Fig. 1. The Fig. 1' direct connection between positive terminal III (solenoid motor) and terminal I20 (relay), is in Fig. 2 carried through the two circuit cut-out switches I08 and I3I. Both terminals of the coil portion I29 (relay).of Fig. 2 are connected in series with terminals I26 and I20 of the signal switch IOI. Any current in the former .therefore, lights the latter.

Functioning of the electrical circuit I32 is as follows: For "off-engine" condition, as was the case in Fig. l, the entire circuit is inoperative. For on-engine condition, it must be assumed that fuel is flowing, that the roller I 99 is between the base of the insulation block I90 and the plate I68 of the pressure responsive switch 9b (1. e., not between plates I81 and I80, due to part inter- .actions explained below), that pressure incident to normal fuel flow has moved the switch carriage I50 into the +P dotted position shown in Fig. '7, and that the ignition switch -I06 is "on". Under the above stated conditions, electric cur rent from the plus" pole of the battery I05 is delivered to terminals I23 (panel), I24 (lamp), I2I (relay) and to the plate I (pressure responslve switch). Before such current can return to the minus pole of the battery I05, from the remaining terminals I26 and I26'of the signal lamp IOI or the terminal I2I of the relay I04, certain parts illustrated in Fig. 2 must undergo physical displacement. In the 'case of the signal lamp IOI, either the push button I2] utilized to test working condition of the light element installed therewithin must be pushed down (thereby connecting terminal I28 with negative tersang in resist the aforesaid minal I34 of the panel I331!) or the metallic roller I99 of the pressure responsive switch 91) must assume a position between the metallic contact plates I81 and I88 as shown in Fig. 7 (thereby flrstly directly inter-connecting terminals I23 and I25 of the panel I331), and, as a result of such common inter-connection, secondly continuously connecting the plus" pole of the battery I with terminal I26 of the signal lamp ll", resultin in continuous illumination of the same due to common inter-connection between additional terminal I28 thereof and the negative terminal I34 of the panel I33b) In the case of the relay I04, whenever the signal lamp IOI is illuminated, due to "closing of the pressure responsive switch 917 (as discussed above), current is also continuously flowing from the plus pole of the battery I05 directly through the coil portion I29 of the relay I04 and from the negative terminal I34 of the panel I33b directly back to the minus pole of the battery I05. The part played by coincident closing of the contact portion of the relay I04 can now be explained.

Let it be assumed, in Fig. 2, that switches I06 and I08 are in an on position and that the fuel pump 6 has not only exhausted the container I,

but that suflicient time has elapsed to effect simultaneous pressure drop in both the by-pass portion of the switch pressure regulator I36 and the cavity I40 of the pressure responsive switch 9b, resulting in upward movement of the switch carriage I50 into the -P position indicated in Fig. 2. The aforesaid upward carriage movement effects automatic closing" of both the pressure responsive switch 9a and the relay I04, resulting in current from the positive terminal I23 of the panel I33b passing directly through the'solenoid motor I02 and back to the negative terminal I34 of the panel I331) (through the terminals I2I and I20, the switches I08 and I3I, and the negative terminal of the solenoid motor I02) Impulses from the solenoid I02 thereupon effect simultaneous turning of the ratchet wheel 421i and thevalve 32 until the long end of the L- shaped passageway 34 of the latter passes into registration with inlet 2% of the housing 28. As a result-of the above registration, fuel from the newly connected container 2 immediately commences to'fiow into the fuel pump 6, from whence it passes directly into the switch pressure regulator I36. It should be noted, at this point, that the tripping cam I38b now approximately occupies the present (Fig. 2) indicated position of the tripping cam I38a. With lifting of the conical valve 2i 9 of! the seat provided in the housing 202, pressure transmitted by the by-pass 206 to the cavity I40 of the pressure responsive switch 9b causes the switch carriage I50 to move into the dotted +P" position indicated in Fig. 2. This latter carriage movement effects contact between the above mentioned tripping cam I38b the container 2 causes complete repetition of the operating cycle set forth above.

In the third embodiment of my invention, I not only accomplish the two objectives enumeratedin connection with the first and second embodiments thereof in an improved manner, but, in addition, I accomplish a third object discussed in detail below. In place of the solenoid motorratchet "drives illustrated in Figs. 1 and 2, my third embodiment employs a unitary selector valve drive for accomplishing turning of the extension shaft 31, and thereby, actuation of my selector valve 4. By the further addition of a solenoid energized clutch, I am also able to acand the cam I96 provided upon the hollow bar I94, causing the metallic roller I99 to be discomplish full manual adjustment of the selector valve 4 in both clockwise and counter-clockwise directions at all times. In the means for accomplishing automatic turning of the aforesaid selector valve, I provide a mechanism capable of accomplishing very exact registration of the selector valve 4 upon connection with any container in which fuel still remaians unexhausted. In addition, where registration with an empty tank is encountered, I provide additional means for uniformly continuing valve rotation until such time as registration is accomplished with a still unexhausted container. 7

In connection with the last named improvement, I substitute for the hydrostatic fuel level gauges illustrated in Figs. 1 and 2, electrical fuel level gauges of the remote reading type sho'wn in Fig. 3. I am able to accomplish the continuous valve turning feature noted above through incorporation, in the tank elements of my electric fuel gauges, of a special contactor the detailed nature of which is fully discussed below.

In the schematic showing of Fig. 3, I have illustrated only such parts commonly used in the second and third embodiments of my invention as are essential to an understanding of the character and functioning of my new selector valve drive and substitute electrical remotely reading fuel level gauges. I have previously stated, at the commencement of this specification, that those parts which bear the numerical designa-. tion I through I0 are common to all three embodiments 6! my invention. At the top and mid-portions of Fig. 3 there are represented in diagrammatic form, respectively, tank elements 23Ia, 23Ib and 23Ic,'and panel elements 2320, 23217 and 232e, of three remotely reading fuel level gauges supported, respectively, by the fuel containers I, 2 and 3 (i. e., parts 23I a through 23Ic) and the panel 25 (i. e., parts 232a through 2320).

Since it is assumed, in Fig. 3, that the fuel container I is in "tank empty condition and that the fuel containers 2 and 3 are in "tank full condition (as is also the case in Figs. 1 and 2); a contactor arm 233 of the tank element 23Ia Is seen in maximum counter-clockwise position with respect to a rheostat 234 provided with plus terminal 235 and minus terminal 236. The counter-clockwise side of the contactor arm 233 is provided with a bumper block 231 (of insulating material) for 'closing the points" of a breaker 238. One end of both the rheostat 234 and the breaker 230 is served by the common terminal 235. The other end of the breaker 239 is provided with a plus terminal 239. It will be noted that the terminal 236 of the rheostat 234 is directly grounded.

The panel elements 232a, 232b and 2320 are each provided with a grounded terminal 240, a.-

plus terminal I (all of which are commonly connected to the "plus pole of the battery II! aaazsve through a "gauge circuit cut-out switch 242, a fuse 243 and a resistance 244), a second plus terminal 245 (each of which is separately connected to a terminal 235 of a tank element 23!), and a terminal 246, (each of which is connected to the pivoted end of a separate contactor arm 233 of a tank element 23!). In combination with a leg-end off, the above panel elements are symmetrically spaced about the extension shaft 31 at 90 degree intervals (the legend of! lowermost). The prior relationship, in Fig. 1, between the arrow 43 provided upon the control handle 46 and the long end of the L-shaped passageway 34 provided in the se1ector-va1ve 4, between the remotely reading gauges (represented in Fig. 3 by parts 232a, 2321) and 232c) and the three inlet ports 29a, 29b and 290 of the selector valve 4, and between the last named inlet ports and the fuel containers 2 and 3, is retained in Fig. 3. While showing of the ignition switch !66 upon the panel 25 is retained; for diagrammatic reasons, showinghf the circuit cut-out switch I68 is shifted to the bottom of Fig. 3. While the latter switch implies manual operation, it is of course to be understood that the same can be automatically operated by fluid pressure or electric current created by starting of the engine.

In the third embodiment of my invention, I substitute a unitary selector valve drive 241 (shown in Figs. 3 and 4) in lieu of the ratchet wheel 42b, the solenoid motor -!62, the circuit N cut-out switch !3! and the hinged dog 229 of the second embodiment of my invention (shown in Fig. 2). The drive 241 is'composed of a motor element 248, a clutch element 249, and a shaft element 256, the latter two of which are encased within a housing 25!. The motor element 248 consists of a small direct current motor 252 having a geared-down drive shaft 253 to the open end of which is fixed a driving bevel gear 254.

The clutch element 246 consists of a solenoid 255 fixed to the housing 25!, and an engaging portion 256 rotatably supported by a, journal boss 251 forming an integral part of the housing 25!, The latter engaging portion consists of a centrally flanged sleeve 258 with square hollow interior slidably engaged by a clutch member 259, a sleeve cap 266 performing the dual objects of a retainer for a compression spring 26! (constantly forcing the clutch member 259 upwardly against the plunger rod of the solenoid 255) and of a bushing rotatable within the journal boss 251. To the upper exterior end of the centrally flanged sleeve 256 is fixed a driven bevel gear 262 held at all times in operable mesh with the driving bevel gear 254. There is jointly journalled to the driven bevel gear 262 and the centrally flanged sleeve 258 a disk 263 (of insulating material) provided with tripping cams 264 (shown in Fig. 3). Relative rotational movement of the disk 263 with respect to a later referred to driven bevel gear (fixed to the centrally flanged sleeve 258) is controlled by a coil spring 265, a diagrammatic side elevation of which is shown in Fig. 3. There is finally journalled to the uppermost exterior of the centrally flanged sleeve 256 the combination clutch member-idler gear 266 referred to in the above sentence.

The member-gear 266 normally remains stationary during those 2periods in which the centrally flanged sleeve 58 is being rotated by the motor element 246. However, if during such rotation, the solenoid 255 is energized, an annular serrated under surface 261 of the clutch member 259 is forced downwardly into driving engagement with an annular serrated over-surface 266 of the combination clutch member-idler gear 266 by a plunger rod 268 of the solenoid 255, resulting in like rotational movement of both the driven bevel gear 262 and the member-gear 266. Since the last named part'is in operable engagement with the shaft element 256, secondary rotational movement of the latter element will also be accomplished.

The shaft element 256 of the unitary selector valve drive 241 is composed of a driven portion 216 and a switch portion 21!.; The driven portion 216 consists of a driven gear 212 and a disk 213 (of insulating material) provided'with tripping cams 214a, 214b and 214a. The driven gear 212 and the disk 213 may be fixed to a driving flange 215 provided on the extension shaft 31 in any suitable manner. The extension shaft 31 is supported in the housing 26! by means of a lower bearing 216 and a split upper bearing 211. The latter bearing is fixed with respect to the housing by means of a split cover plate 218 having adjustment openings 218 normally sealed by a dust cover 286 secured to the plate 218 by means of a retaining ring 28!.

Referring to both Figs. 3 and 4, .it is seen that the switch 21! of the shaft element 256 is com- 'single circuit breaker 283.

posed of a three circuit interruptor 262 and a The interruptor 282 consists of a cylinder 284 (of insulating material) fixed to the extension shaft 31 and having three commutator segments 266a, 2651) and 2650, symmetrically disposed (in end elevation), respectively, with associated tripping cams !36a, !38b and I380 provided upon the control disk !31 (common to Figs. 1, 2, 3 and 4) of three separate brushes 286a, 26Gb and 266a; and of a three fingered single terminal brush 281. The

, latter brush is directly connected to the makeand-break terminal !2! of the relay !64, while the former three brushes are directly connected, respectively, to a terminal 239 of the tank ele-. ments 23m, 23|b and 23!c. Since the remaining (make-and-break) terminal !26 of the relay !64 is directly connected to a "plus terminal 288 of the solenoid 255, it is at once evident that successive closings of the breaker 236 of 23m, the breaker 238 of 23!b and the breaker 238 of 23!c" (due to tank empty" condition), in combination with like successive closings of parts 286a265a-281" and the make-and-break portion of the relay !64, of parts 286b285b-261- and the make-and-break portion of the relay I64,

and of parts "2860-2850-281 and the makeand-break portion of the relay I64 will cause energization of the clutch solenoid 255. So long as the aforesaid energization continues, any turning of the driving bevel gear 254 of the motor 252 will induce counter-clockwise turning at the extension shaft 31 as viewed in Fig. 3.

. The single circuit breaker 283 (best shown in Fig. 3) is composed of a pivoted contact arm 289 (of insulating material) partially cut away upon one side to permit free counter-clockwise movement of a leaf spring 296 affixed thereto and having a cam 29! fixed to its mid right hand portion and a contact point 292 fixed toits top left hand portion, the open end of said arm being bent slightly to the left and terminating in a cam 293 oppositely and outwardly disposed with respect to the spring cam 29!. The breaker 283 is completed by addition of a tension spring 294, utilized to maintain the'cam 233 in continuous contact with the disk 213. A contact point 295 is operably associated with the contact 292 provided upon the top left hand portion of the leaf spring 290.

The lower half of the diagrammatic showing of Fig. 3 is completed by incorporation of a signal lar-p 296 having its "plus terminal 291 directly connected to the metallic contact plate I88 of the pressure responsive switch 91) and by the further addition of a variable resistance 298 having a terminal 299 similarly connected to the circuit cut-out switch I08 and a terminal 300 connected to a plus terminal 30I of the motor 252. To simplify future reference to electric circuits appearing at both top and bottom of Fig. 3, that portion of the wiring commonly interconnecting the plus pole of the battery I05 with parts 242--243-244--232a through c'fwill be referred to as a gauge" electric circuit 302 and the remaining wiring of Fig. 3 will be referred to as a selector valve drive" electric circuit 303.

Having fully described the construction and in the main the operation of the unitary selector valve drive 241, I now propose to disclose how the various parts thereof cooperate with the pressure responsive switch 9b, the control disk I31 and the electric circuit 303 embracing the ignition switch I06, battery I05, signal lamp 296, circuit cut-out switch I08, relay I04 and variable resistance 298, to eifect automatic turning of .the selector valve 4 from any tank empty" condition to a "tank full condition. In lieu of the ratchet wheel 42a, the hinged dog II2, the solenoid motor I02 and the motor control I03 of Fig. 1 and the ratchet wheel 42b, the hinged dog 229, the solenoid motor I02 and the circuit cut-out switch I3I of Fig. 2, I substitute the unitary selector valve drive 241 in the third embodiment of my invention. The Fig. 2 positionings' of the fuel containers I, 2 and 3, of the selector valve 4, of the control disk 31 and'the pressure responsive switch 9b associated therewith, of the panel 25, and of the fluid associated parts to the right of the panel 25,- remain unaltered in the third embodiment of my invention,

Let it be asssumed, in Fig. 3', that switches I06 and I08 are in an on position and that the fuel pump 6 has not only exhausted the container I, but that sufi'icient time has elapsed to efiect simultaneous pressure drop in both the new pressure regulator I36 and the cavity I40 of the pressure responsive switch 9b, resulting in left hand movement of the switch carriage I50 into the nation clutch member-idler gear 260 and the driven gear 212 forming a fixed part of the extension shaft 31.

As the driven gear 212 commences its counterclockwise rotation (see Fig. 3), thetripping cam 214a of the disk 213 forces the contactor arm cam 293 to the right, breaking" the contact points 292 and 295 and positioning the leaf spring cam 29I in the path of an oncoming disk cam 264. Two results are obtained by the foregoing. Firstly (assuming, for the mere purpose of simplifying the illustration in point, momentary disconnection between the breaker '2" of the tank element 23Ia and the separate brush 266a of the three circuit interrupter 202), stoppage of current flow to the clutch solenoid 259 causes the solenoid plunger rod 269 to return to -P position indicated. The aforesaid left hand carriage movement effects automatic closing of the pressure responsive switch 9b, resulting in electric current from the plus pole of the battery I05 being quadruplicately grounded, i. e. firstly at the signal lamp 296 (through parts I06I81I99--I88296), secondly at the relay I04 (through parts I06I81I99-I88- I08I29), thirdly at the motor 252 (through p a r t s I06--I81--I99I88I08-298252) and fourthly at the clutch solenoid 255 (through p a rt 5 I06-I81I99I88I06290292 294-255). The aforesaid current flow results in lighting of the signal lamp 296, which in combination with the panel elm'ent 232a now gives double indication that the fuel container I is in tank empty condition; results in closing of the make-and-break portion of the relay I04 (the special significance of which is dealt with below); results in immediate rotation of the driving bevel gear 254 and therefore the disk 263 (momentarily); and results in immediate extension of solenoid plunger rod 269, causing simultaneous though opposite rotation of the combithe positioning of Fig. 3, resulting in immediate rotational stoppage of the disk213. Secondly, positioning of the leaf spring cam 29I in the path of an oncoming disk cam264 momentarily delays rotation of disk 263 in a clockwise direction until the spring 265 becomes sufliciently tensioned to cause one of the tripping cams 264 to bend the leaf spring 290 to the left sufliciently to produce closing of the contact points 292 and 295. Since so long as the pressure responsive switch 81) remains closed, the motor 252 continues to turn; the tripping ca'm 2140. of the disk 213 moves past the contactor arm cam 293 and the disk 213 continues a quarter turn until the oncoming tripping cam 214b contracts the contactor arm cam 293. In the last named positioning of the disk 213, the long end of the L-shaped passageway 34 of the selector valve 4 is in registry with the inlet 29b operably connected to fuel container 2, and the fuel pump 6 commences to build up joint pressures in the pressure regulator valve I36 and the cavity I40 of the pressure responsive switch 9b. As the tripping cam 21"; of the disk 213 moves the contact arm cam 293 to the left, the tripping cam I38b of the control disk I31 moves into alignment with the cam I" of the pressure responsive switch 912. Tensioning of the spring 265 is so calculated as to permit full right hand movement of the switch carriage I 50 into the l-P dotted position of Figs. 2 and 3. Since the cam I96 (switch 9b) and the tripping cam I381) (control disk I31) are in longitudinal alignment, the contactor arm element I86 is ultimately rotated in a counter-clockwise direction by full right hand movement of the switch carriage I 50, causing opening of the pressure responsive switch and complete rotational stoppage of the unitary selector valve drive 241.

Upon exhaustion of the fuel container 2, the switch carriage I 50 again moves into the closed" positioning of Fig. 3, and the above recited operation cycle of the unitary selector valve drive 241 is-again repeated, this time in conjunction with" tripping cam 2140 of the disk 213 and the tripping cam I38c of the control disk I31; I have now progressed suificiently with my explanation of the operating characteristics of the unitary selector valve drive 241 to discuss in detail the special significance of the electric current from the plus pole of the battery I05 being grounded at the relay I 04 (through parts I06-I81I99 I86l08l29) in conjunction with simultaneous closing of a breaker 238 of a tank element 23Ia through c and simultaneous electrical interconnection between a separate brush 286a through c, a commutator segment 285a through c and the three fingered single terminal brush 201.

For illustrative purposes, only. letit be assumed .that instead of the "full" showing of Fig. 8, the fuel container 2 (due to air combat or mechanical defect) is in a tank empty condition. Then, when the tripping cam 2142) of the disk 213 passes from its Fig. 3 positioning into registry with the contact arm cam 293, the commutator segment 2851) will assume the present Fig. 3 positioning of the commutator segment 285a. Thereupon, current from the plus pole of the battery I05 will pass directly to the ground of the clutch solenoid 288 (through parts "242-243-244- 232b--23lb through closed 233-290b-285b- 28ll04--255"). This will result in short circuiting out the delaying effect of the hereinabove described initial opening, then closing of the contact points 292 and 295, resulting in elimination of selector valve pause when registering with an empty tank. Much time is thus saved in continuing rotation of the selector valve 4 until engagement with the fuel container 3 is eifected.

In the description of the first embodiment of my invention, I made reference to certain xisting limitations in present fuel delivery systems requiring pressure control at source of consumption. I have avoided these limitations, in the first three embodiments of my invention. by employing an engine fuel injector l0 having a pressure relief valve 228 (shown in Fig. 1) forming an integral part of theinjector proper and by further providing piped connection between an outlet of the said relief valve and the inlet side of the fuel pump 6. Since unsupercharged engines, or engines in which the superchargers do not effect the carburetors, are normally equipped with fuel injectors or carburetors designed to operate under fixed fuel inlet pressures ranging from 3 to 15 pounds, for purely illustrative purposes I adjust the valve 228 such that it will by-pass to the inlet side of the fuel pump 6 all fluid pressures created in the pump outlet in excess of approximately three pounds per square inch. No such precautions, however, have been incorporated in the above referred to systems. These still persist in placing the fuel pressure regulator adjacent to the fuel pump, with inlet side connected to pump, outlet and outlet side connected to pump inlet, such that any excess fluid pressure (over that required by a source of consumption such as a fuel injector or carburetor) will be immediately by-passed to the pump inlet. The operating limitations of an aircraft incorporating such a parts arrangement are briefly discussed in the second paragraph immediately below.

In Fig. 5, I disclose a modification in the fuel delivery portions of the second and third embodiments of my invention. Therein, I duplicate prior usage of the fuel strainer 5, the pump 6, the wobble pump I, the switch pressure regulator I38 and the major portion of the engine fuel injector l0. From the last named, I omit the pressure relief valve 228 and the by-pass piping to the inlet of the fuel pump 6. To continue the function previously performed by the omitted relief valve 228 and by-pass piping. I add a fuel pressure regulator 304 with inlet connected to the outlet of the switch pressure regulator I38 by means of a pipe 305 and'outlet connected to the inlet of the fuel pump 6 by means'of a second pipe 306. In addition to the above, I add an aspirator 301 with a Venturi inlet 308 in continuation of the former pressure relief valve outlet of the engine fuel injector l0, with a main inlet 309 connected to the outlet of the switchs-pressure regulator I36 by eliminator 9c and pressure responsive switch 90 connected with a main outlet 3| l of the aspirator 301 by means of a pipe 3l2. Previous interconnections between the outlets of air-vapor eliminators 8a and 8b and the inlet of the fuel injector l0 are retained. A second outlet provided in the fuel pressure regulator 304 and an outlet provided in the (Fig. 2) lin connecting the lower cavity I of the pressure responsive switch 9b with the induction system of a supercharged aircraft engine are piped to a two-way valve 3l3. In Fig. 5, the above second outlet is shown directly vented to the atmosphere.

Before proceeding with a detailed description of further new parts appearing in Fig. 5, or disclosing operation of my improved system as a whole, I wish to again return to the above discussed limitations in many existing fuel delivery systems. With the two exceptions of complete omission of the switch pressure regulator I30 (since same is peculiar solely tomy invention) and substitution of a conventional ball and spring" type pressure relief valve (or equivalent) in lieu of my new and novel type of fuel pressure regulator 304, let it be assumed that an aircraft having its fuel tanks located well below the level of the fuel strainer 5 and an engine in which the supercharger does not affect the fuel injector I0 is equipped with the parts showing of Fig. 5. Let it be further assumed that the conventional fuel pressure regulator mentioned above is set at approximately three pounds per square inch and that the aircraft takes ofl and maintains steady increase in altitude. Under such conditions. as the atmospheric pressure upon the top surface of the fuel of the fuel tank then operably interconnected with the fuel pump 6 steadily diminishes, the magnitude of the suction necessary to raise the fuel into the rotor portion of the fuel pump 6 steadily increases. If climb is continued to an altitude of between 23,000 to 28,000 feet, the

its maximum suction capacity and will have ceased further fuel delivery. However, long before any such altitude has been reached, steady climb will have increased the approximately onehalf pound per square inch suction required for ground transfer of fuel from "tank-to-pump to a magnitude equal (though opposite in sign) to the positive fuel pressure of three pounds per square inch maintained by the conventional fuel pressure regulator. Thereafter, no further increase in the magnitude of the suction required to transfer fuel from "tank-to-pump can occur, because of continuous pressure by-passing set up at this point by the conventional fuel pressure regulator. Obviously, further increase in altitude will terminate fuel flow in the pipe 3l-0 through starving of the rotor portion of the fuel pump 6. I have personally experienced just such an engine failure during flight test of a fuel system of the character described.

In existing fuel systems incorporating the above limitations, there s a second operating factor which may cause engine failure. If, through human or mechanical defect, the receiving end of a selector valve passageway fails to correctly register with the delivery end of a selector valve inlet, thus introducing a restriction to fuel flow from tank outlet to pump inlet, an increase will occur in the magnitude of the suction necessary to raise fuel into the rotor portion of the fuel pump 5. Such a restriction to fuel flow may readily'assume proportions causing a means of a pipe 3l0 and a combined air-vapor 76 duplication, at ground level or shortly after takeoil, of the hereinabove described continuous pressure by-passing at the fuel pump 8. I now pro- Pose to disclose how the modification in the fuel delivery portions of the second and third embodiments of my invention over omes the limits.

turi 3. The open end of a bellows 3! is adapt-' ed to be fixed to the top surface of th housing 3 by means of a cover plate 3!!) and gaskets 320. The bellows 3|Bris provided with a valve 32! fixed to and depending from the bottom of its closed end. The valve 32l is provided with a holddown spring 322a and compression adiustor 323. The latter includes an adjustor stem 324 with threaded lower end,a spring seat 325 secured to the lower end of the stem 324 and an ad'justor knob 326 fixed to the unthreaded upper end of the stem 324. The cover plate 3!!) is provided with a packing gland 321 and packing gland collar 328 surrounding the adjustor stem 324., The cover plate 3| 9 i provided with an outlet 329. Communication between the sealed interior of the bellows 3|8 and the outlet 329 is established by means of a passageway 33!].

Let us now reapply the operating conditions. presented in the third paragraph immediately above to the actual parts showing of Fig. 5 (note that the two-way valve 3| 3 is vented to the atmosphere). With starting of the engine, if a fuel pressure of three pounds per square inch is to be maintained in the pipe 335, the adjustor 323 (of regulator 304) must be so set that upward pressure on the mean base area of the bellows M8 is exactly counteracted by the combined downward pressure of suction on the valve 32d and compression of the spring 322a. Upon accomplishment of the aforesaid setting, let it be assumed that the aircraft takes off and maintains steady increase in altitude. As the onehalf pound per square inch suction required for ground transfer of fuel from tank-to-pump steadily increases (with increasing altitude), the original sea-level atmospheric pressure within the interior of the bellows 3H3 undergoes like pressure decrease (due to its direct communication with the atmosphere) such that these two opposing pressures merely nullify one another (i. e. mere increase in altitude has no regulatory effect upon'seating of the valve 32i) On the other hand, any fuel pressure in excess of three pounds per square inch introduced into the housing 3 by the pipe 305 will cause immediate unseating of the valve 32I through upset of the combined;

downward pressure of the spring 322a and the initial or ground suction on the valve 32 I. I deire to note, in passing, that by usage of the Venturi portion of the combined valve seat and venturi 311,1 am able to use a smaller orifice to pass a given volume of fuel without unduly increasing the pressure or suction necessary to maintain such flow. The aforesaid usage of a venturi also tends to create a less turbulent flow and therefore decreases presence of vapor lock In the above paragraph, I described functioning of the fuel pressure regulator 304 with reference to an aircraftequipped with an unsupercharged engine or an engine in which the supercharger does not affect the fuel injector 10. Let

buretor. In such an installation, the fuel pressure of the engine injector or carburetor is re-. ferred to the aforesaid air altitude.

inlet pressure at given Assuming a supercharger providing sea-level condition and an initial (ground) setting of three pounds per square inch for the adjustor 322, the fuel pressure increase required in the pipes 305 and 3H1 of Fig. 5 (after aircraft take-on and steady increase in altitude) is equal to the sum of said initial three pound pressure and the pressure difference between sea-level atmospheric pressure and the atmospheric pressure at any then given altitude. To obtain the foregoing fuel pressure increase, it is necessary only that one adjust the two-way valve 3l3 (of Fig. 5) such that the interior of the bellows M8 is in constant communication with the induction system of. the aforesaid supercharged engine. As the original ground atmospheric pressure surrounding the aircraft lessens in magnitude, with continued increase in altitude, the aforesaid induction system increases in magnitude the inius now consider an aircraft equipped with an v engine in which the supercharger controls the air inlet pressure of engine fuel injector or cartial (ground) sea-level atmospheric pressure within the interior of the bellows 3l8 (because of its common interconnection with the aforesaid bellows interior). It thus obviously follows that for each pressure increment added to the interior of the bellows 3|8, a like pressure increment must be added to the exterior of the bellows M8 (by the fuel pump 6 through the interior of the pipe 305), if the whole is to remain in equilibrium.

In Fig. 10, I show structural modification of the fuel pressure regulator 304 of Figs. 5 and 9. In lieu of the cup-shaped housing 3, I substitute horizontally disposed forward housing 332 and aft housing .333. I further substitute a holddown spring 3221) for the former spring 322a for reasons more fully discussed in detail hereinbelow. Itwill be noted that the combination valve seat and venturi 3l'E-is now horizontally disposed in continuation of the horizontal inlet 3|5 and that the bellows 3!!! is turned endfor-end such that its interior is continuously in communication with the vertical outlet 3"; provided in the forward housing 332. The latter requires mountin of the valve 32! upon a stem 334 fixed to the closed end of the bellows 3|! by means of a mounting disk 335. With addition of gaskets 320, 320 and 329, the forward housing 332, the aft housing 333 and the unaltered cover Plate 3| 9 are assembled together as indicated in Fig. 10.

Let us first consider utilization of the modified fuel pressure regulator in connection with unsupercharged engine condition." With starting of the 'engine, if the fuel pressure of three pounds per square inch is to be maintained in the Pipe 305, the adjustor 323 (of Fig. 10) must be so set that rearward (right hand) pressure on the valve 32! is exactly counteracted by the combined forward (left hand) pressure of suction on the mean base area of the bellows M8 and compression of the spring 3221). Obviously, compression characteristics of the latter are far less in magnitude that those of the holddown spring 322a. Upon accomplishment of the aforesaid setting, let it be assumed that the aircraft takes off and maintains steady increase in altitude. As the onehalf pound per square inch suction required for ground transfer of fuel from the tank-to-pump' steadily increases (with increasing altitude), the original sea-level atmospheric pressure within the rear housing 333 undergoe like pressure decrease (due to its direct communication with the atmosphere) such that these two opposing pressures (acting one within and one without the bellows 313) merely nullify oneanother (i. e. mere increase in altitude has no regulatory effect upon seating of the valve 3). On the other hand, any pressure in excess of three pounds per square inch within the pipe 335 will cause immediate unseating of the valve 32! through upset of the combined forward pressure of th spring 3221) and the initial or ground suction upon the mean base of the'bellows 3 l 3.

Utilization of the modified fuel pressure regulator should next be considered in connection with increasing carburetor air inlet pressure supercharged engine condition." The two-way valve 3" (of Fig. 5) is first adjusted such that the interior of the forward housing 333 is in constant communication with the induction system of the aforesaid supercharged engine. Then, as the original ground atmospheric pressure surrounding the aircraft lessens in magnitude, with continued increase in altitude, the aforesaid induction system increases in magnitude the initial (ground) sea-level atmospheric pressure within the interior of the forward housing 333. It therefore obviously follows that with properly interportioning of "bellows and valve, for each pressure increment added to the exterior of the bellows 3 l3 (through the rear housing 333) a like pressure increment must be added to the seated portion of the valve 32! (by the fuel pump 3 through the interior of the pipe 335) if the whole is to remain in equilibrium.

Before proceeding with the description of the modified combined air-vapor eliminator 3c and pressure responsive switch 30, I desire to make brief comment with reference to the aspirator 331. Due to its close proximity to the engine} into which it feeds fuel, the engine fuel injector I3 is subject to considerable heat transfer. This has a tendency to prematurely vaporize stagnant fuel therewithin. The latter I avoid b assuring constant fuel circulation from the Venturi outlet 333 of the aspirator 331 into the inlet 43 of the air-vapor eliminator 30, from the outlet 41 (of the latter) into the inlet of the engine fuel injector I3, and from thence through body portion to outlet of the aforesaid injector I3.

Due to the more or less schematic nature of (depending from said ring) and of an upper housing 341 fixed to the top surface of the annular ring 342. The bottom of the lower housing 345 is cupped out to form a journal guide for the tube 51 (of the float 53). The valve seat 33 is fixed to an aperture provided in the top of the upper housing 341 such that it acts as a base guide for the spring 331. The outer diameter of the annular ring 342 is in turn guided by a cupped sleeve 343. The latter is provided with vent holes 343:: and 343b, a turned over mounting flange 353 and a mounting gasket 35l. Immediately upon the top of the mounting flange 353, I place a thin annular disk 352 to the lower inner surface of which I fix the upper end of a flexible liquid sealing element or bellows portion 353. The lower end of the bellows portion 353 is also fixed to the top surface of the annular ring 342. The utility of the latter bellows portion will be discussed in detail hereinbelow.

The cup-shaped housing 44 is provided with a cover plate-housing 354 (secured by conventional screw-lockwasher means) A vertical cavity 355, of the housing 354, is provided with a sleeve 353 adapted to act as a primary guide for the float guide 333. The top of the housing 354 includes a spring cavity 351; vent line passageways 12, 13 and 14; and a contactor pin hole 353. A contactor pin 353 (of insulating material) with major portiondepending from the bottom surface of a contactor housing 333, is adapted to be vertically slidably guided by the hole 353 (in the housing 354). Upward movement of the pin 353 is required to "open circuit" the insulated movable contact 343 with respect to the grounded fixed contact 333. Obviously, the fixed contact 333 may be insulated from the housing 333, if desired. -The contactor housing 333 can be fixed to a shelf 33l provided upon the top outer surface of the cover plate-housing 354 by any of several well known conventional means.

The combined air-vapor eliminator 3c and 7 Fig. 11, I have reduced showing of details not level approximating the middle of the last named resulting in opening of a fixed contact 333 con- 60 nected to a binding post 333 and a movable con-- tact 343 connected to a binding post 341. The contacts 333 and 343 perform the same functions as the contacts 33' and 33 of Fig. 6. Upon exhaustion of any fuel container operably connected to the air-vapor eliminator 3c (of Fig. 11) the reserve fuel contained in the cup-shaped housing 44 is pressure fed through the outlet 41 by the spring 331, since continuing operation of the fuel pump 3 prevents fuel escapage from the inlet 43 (of housing 44) I provide the following new or substitute parts in Fig. 11. The slidable float guide 333 consists of an annular ring 342 with vent holes 343 and vent hole. So far, air originally occupying the empty air-vapor eliminator 30 has found ready escape through the open valve seat 33 and vent passageways 12, 13 and 14. Thereafter, further fuel'flow divides itself in inner zone A and outer zone B flow. Due to air trap, the latter does not progress to the top of the cup-shaped housing 44. The former, however, ultimately completely fills the upper housing 341. When fuel in the inner zone A reaches a point slightly above the buoyancy level of the float 53, the valve 34 closes the valve seat 33. Thereafter, pressure from the fuel pump 3 must be relied upon, if further liquid rise is to be accomplished within zones A and B.

5 Ingress of further fuel, under steadily increasing 333 (and contents) upward movement until its uppermost surface eflects vertical rise of the pin 353. So long as the fuel pump 3 continues normal functioning, the contacts 333' and 343 will remain in open-circuit" condition and the engine fuel injector or carburetor connected with the outlet 41 (of the housing 44) will continue 344, of a lower housing 345 with vent ho1es 343 to receive fuel under a predetermined pressure.

In addition to the above, during the time interval between exhaustion of a fuel container; automatic turning of the selector valve 4 to an unexhausted fuel container, and passage of fuel from the new container outlet to the air-vapor eliminator inlet, the engine fuel injector or carburetor will continue to be fed reserve fuel under pressure from the cup-shaped housing 44 (of the eliminator 8c).

In the first three embodiments of my invention, I illustrate association of the pressure responsive switches 9a, 9b and 90 with the fuel delivery portion of my fuel system: -I do not desire, however, to infer thereby that general application of my pressure responsive switch must be so limited. In Fig. 12, I show an embodiment of the aforesaid switch adapted for association with the source selector portion of the first embodiment of my invention. During operation of the switches 3a, 9b and 3c (shown in Figs. 6, 7 and 11), open-circuit" condition thereof is automatically maintained so long as the fuel pump 6 is delivering fuel toan engine fuel injector inlet or a carburetor inlet under a predetermined (positive) pressure. In the pressure responsive switch 9d (shown in Fig. 12) open-circuit condition is automatically maintained so long as the fuel pump 6 is connected to and continuously removing fuel from an unexhausted fuel container under a predetermined (negative) pressure or suction. It is of course to be understood that the pressure responsive switch 9d may equally well be applied to a pipe through which fuel is being continuously gravity fed, as I employ conventional venturi means to effect pressure drop in the bellows element of my switch.

In Fig. 12, I place a venturi 362 adjacent to the fuel strainer 5. Obviously, any insertion between selector valve outlet and fuel pump inlet will serve equally well. The venturi 362 includes a main inlet 363 connected to the outlet of the selector valve 4, a main outlet 364 connected to the inlet of the fuel strainer 5, and a Venturi inlet 365 connected with the outlet of the pressure responsive switch 9d. The last named consists of a bellows element 366 supported by a cover plate 361 and a contactor element 368 fixed to the bottom of a cup-shaped housing 369 which last named housing is provided with a vent hole 316. The bellows element 386 comprises a bellows 31! with open end soldered or otherwise fixed to the cover plate 361, the closed end thereof being provided with a depending contactor pin 312 (of insulating material), and a compression spring 313. The upper end of the spring 313 is guided in a recess 314 provided in the cover plate 361, which also includes an outlet 315 connected to the Venturi inlet 365 by a short pipe 318. The contactor element 368 comprises a fixed contact 311 supported by a threaded post 318 (of insulation material) fixed to the cupshaped housing 369 by means of a lock nut 319 and a movable contact 388 supported by a second threaded post 38! (of like material and fixity). The movable contact 388 includes a leaf spring 382 tensioned such that upward movement of the contactor pin 312 effects immediate separation between the movable contact 380 and the fixed gontact 311 (i. e. produces open-circuit condiion).

Operation of the pressure responsive switch lid is as follows: During that period between any one fuel container exhaustion and renewed fuel flow from the next unexhausted fuel container, fuel momentarily disposed between selector valve and fuel pump first ceases to flow and then upon renewed fiow becomes such a mixture of air and fuel that passage vof the aforesaid mixture through the venturi 362 greatly reduces suction 5 effect" upon the Venturi outlet 365. As long as mixed passage of air and fuel continues through the venturi 362, a closed-circuit condition prevails. However, with renewed fuel flow, increased pressure drop in the Venturi outlet 38! depresses the bellows 31l, causing upward movement of the contactor pin 38!) and thereby immediate open-circuit condition.

In Figs. 13 and 14, I disclose a very simple alteration in the three circuit interrupter 282 (of 15 Figs. 3 and 4) whereby the unitary selector valve drive 241, or the altered interrupter in combination with the valve driving means shown in Figs. 1 and 2, may be applied to any aircraft having recesses provided in the bottoms of its fuel containers I, 2 and 3 into which the float portions of tank elements 23la, 23") and 23lc may descend such that "down float" condition indicates tank empty condition. When combined with the pressure responsive switch 25 9d (of Fig. 12), the above may be equally well applied to either gravity or pressure fed fuel dispensing systems. If desired, the tank portions immediately above the aforesaid recesses may be hopper shaped. To save needless addition of further figures, I describe operation of the above modification with reference to the parts showing of Figs. 3 and 4. Obviously, the altered interrupter may be equally well affixed to the extension shafts 31 of Figs. 1 and 2 (plus appro- 35 priate valve driving means interconnection). To

further simplify my illustration, I reduce employment of parts to a minimum. I do not however desire, by so doing, to infer that the new three circuit interrupter 383 (shown in Figs. 13 and 14) shall be limited to interaction only with these parts, nor do I wish to be excluded from same such obvious simplifications in the present parts arrangement of the unitary selector valve drive 241 as omission of the clutch element 249 (through direct motor drive of the driven gear 212), etc.

In Figs. 13 and 14, it will be seen that I so laterally space the three commutator segments 384a, 384b and 3840 that each can be respectively contacted only by separate brushes 286a, 28% and 2860. I further so stagger the circumferential arrangements of the commutator segments 384a, 3841; and 3840 that first 384a, then 384b, then 3840 bridges the gap between the three finger single terminal brush 281 and the three separate brushes 286a, 2861; and 2860. Referring specifically to Fig. 14, with the shaft 31 in such a position as to register the long end of the L-shaped passageway 34 (of valve 32) in registry with the inlet 29a of the selector valve 4 (as shown in Fig. 2), I position the leading (left) edge of the commutator segment 384a angle a past the outer end of the contacting tip of the brush 281. The gap between this tip and the outer end of the contacting tip of the separate brush 286a is designated angle b. The degree value of either is a mere matter of design choice. Not so, however, is the angle 0. Due

to'the 90 degree spacing between the inlets 29a and 29b of the selector valve 4, the angle 0 must also equal 90 degrees. In summation, then, from leading edge to trailing edge the commutator segment 384a extends angle d1 and from leading edge to the outer end of the contacting tip of the separate brush 286a it extends ngle 

